Precision sharpener tool

ABSTRACT

A precision sharpening tool is disclosed, having an opposing sharpening elements arranged to form a generally “V” shaped sharpening slot and first and second elongate guide members arranged on opposite sides of the sharpening slot which comprise mating toothed spur gears arranged so that turning the guide pin element of the first guide member simultaneously turns the guide pin element of said second guide member in aligned mirrored movement.

This invention relates to a novel system and tool for sharpening thecutting edge of knives and the like, being particularly suitable formaintaining precision sharpening angles to enable consistent, qualityedge sharpening.

BACKGROUND OF THE INVENTION

Sharpening tools are well known in the prior art, for use in sharpeningcutting edges such as the blades of knives and the like cuttinginstruments.

Knife sharpening tools, particularly hand tools and simple automatedtools that are easy to use and provide precision sharpened edges ofconsistent quality continue to be desired by the consuming public.Sharpening tools generally used by the consuming retail public aregenerally referred to as pocket and hand knife sharpeners. Pocket knifesharpeners generally comprise a sharpening element such as an abradingcomposite stone or the like material, that is generally packaged in apouch or the like for pocket carrying. The size of the stone isgenerally small for convenient pocket carrying, which makes the hands onmanipulation of the small stone during the sharpening process generallyunsafe for the user and generally requires significant hand manipulationskills to conveniently and accurately sharpen a cutting edge.

A very popular knife sharpener generally comprises opposing disks,blades or composite stone manufactured from carbide, abrasive or thelike materials which are generally arranged so that the knife blade canbe moved through a “V”, shaped slot or the like, with opposite sides ofthe edge thereof engaging static or revolving disks or the like to shavesides along a bevel of the edge of the knife to sharpen the edge. Suchtools are useful, but are limited in the quality of sharpened edge thatcan be attained and thus the durability and usefulness of the knife sosharpened.

For general purpose cutting, an efficient knife blade cutting edge isgenerally considered to be one in which the edge is formed at the apexof opposite sides of a knife blade beveled to about a 20 degree angle tothe center line of the plane of the blade. Blades so sharpened generallyretain their edge longer, have reduced binding of blade sidesparticularly with thick substances being cut during the cutting process,and experience reduced wear at the cutting edge. “V” notch sharpeningarrangements are generally designed to fix opposing sharpening disksand/or straight edged sharpening blades in an arrangement forming anabout 40 degree sharpening notch, which if the blade of the knife isheld in perfect position bisecting the notch during the sharpeningprocess, will simultaneously abrade or shave both sides of the bladeduring the sharpening process to about a 20 degree bevel and the edgewill be a precisely formed to its most efficient cutting edge.

Unfortunately, holding a knife blade to perfectly bisect a “V” slotduring the sharpening process requires skilled manipulation of the tool,and frequently the person manipulating the tool ends up producing asharpened knife having different beveled angles on opposite sides of theknife and/or variations in beveled angle along the length of the bladeon the same and/or different sides of the blade. The result is animproperly sharpened knife which though it may have a sharp edge, iseasily dulled and since the sharpened edge is not centered along thethickness of the blade, a blade which tends to tear or bind duringcutting through the thickness of materials.

U.S. Pat. No. 6,626,066 discloses a foldable sharpening tool having anelongate sharpening guide which is compactly foldable or removable forstorage within the tool. Two sharpening guides are arranged on eitherside of a “V” shaped sharpening slot and a guide comprises an eccentricmounted guide cap which can be turned to adjust the eccentric cap towardor away from each other to adjust distance between guides. Though theuse of such guides can theoretically enable the positioning of a knifeblade in an ideal position for sharpening, each guide must beindependently adjusted and the attaining of such ideal position isdependent upon the skill of the user, particularly his/her ability tovisually align the guides within a narrow range of ideal proximity.

It is an object of the present invention to provide a sharpening deviceand system which will enable the production of consistent precisionsharpened edges.

It is a further object of the invention to provide a means for safelyand accurately guiding a cutting edge along a sharpening surface duringa sharpening process.

These and other objects of the invention will become apparent in thefollowing recitation of the invention.

SUMMARY OF THE INVENTION

The present invention is an improved sharpening tool and system,generally comprising unique, self-centering, micro-adjustable sharpeningguides arranged to assure consistent, precision retaining of knifeblades of varying thickness within precision angular tolerances againstopposing element blade sharpening means. By opposing element sharpeningmeans is meant an arrangement wherein a blade is sharpened by meanswhich simultaneously engage and abrade opposite sides of a blade or thelike during the sharpening process.

The micro-adjustable sharpening guides of the invention comprisegenerally parallel, opposing members mounted to a sharpening tooladjacent a “V” shaped sharpening slot formed by opposing sharpeningelements. The guide members are generally arranged to extend from thebody of the sharpening tool and comprise opposing surfaces which supportthe blade to be sharpened in a preferred orientation in the “V” shapedslot during sharpening.

A guide member of the invention comprises a base spur gear element andan eccentric guide pin element. The base spur gear element comprises ashaft having a toothed gear at a first end and an eccentric guide pinelement extending from the opposite end. In a preferred embodiment, thecenterline of the guide pin element is arranged offset from andgenerally parallel to the centerline of the shaft of the spur gearelement.

Guide members are arranged in generally parallel alignment, at oppositesides of an ideal sharpening plane for engaging the knife blade withopposing sharpening means. The toothed gear of a first guide member isarranged to matingly engage the toothed gear of a second guide member,such that rotatably turning the shaft of the spur gear of a first guidemember institutes synchronized rotation of the corresponding shaft of asecond guide member. The gears are in mating alignment so that duringrotation of the guide members, the shafts of the spur gears rotate inposition and the eccentric pin elements of the guide members move towardand away from each other in aligned mirrored movement.

In a preferred arrangement of the invention, the shafts of two or morebase spur gear elements are rotatably mounted in bearing holes arrangedon opposite sides of the plane of the bisect of a generally “V” shapedsharpening slot formed by opposing blade or disk sharpening elements.The base spur gear elements are arranged about equidistant from thecenterline of the “V” shaped slot with their toothed gears in matingalignment generally below the sharpening level of the blades or disks,with their respective eccentric guide pin elements extending upwardly onopposite sides and about equidistant from the plane of the bisect of the“V” shaped slot, generally above the sharpening level. When a knifeblade is to be sharpened, an eccentric guide pin element of a guidemember can be rotated to adjust the spacing between eccentric guide pinelements as may be suitable for the thickness of the knife blade. Aguide member is generally rotated sufficiently so that opposingeccentric guide pin elements closely engage opposite sides of the knifeblade arranged in the “V” shaped slot between the eccentric guide pinelements. Since the guide members are arranged about equidistant fromthe plane of the bisect, mirrored adjustment of guide pin elementstoward and away from each other synchronically maintains the center ofthe space between the guide pin elements and thus the knife blade atabout the center of the “V” shape and at or about the ideal sharpeningplane.

Disks or blades in a “V” slot sharpening arrangement are typicallyoverlapped in opposing staggered orientation to provide a sharpeningslot of about 35-45°, preferably about 40°, with sharpening meansengaging opposite sides of a blade bisecting the slot, at an angle ofabout 20° to each side of the blade to be sharpened. Once set to thethickness of a blade, the guide members of the present invention retainsthe blade in a precision manner along about the center bisect of the “V”slot as the blade is being drawn through the slot, overcoming inadequatemanipulation skills of the user and thus sharpens the blade to its mostefficient edge for cutting a variety of materials.

In one embodiment of the invention an elongate guide pin element isformed integral to the shaft of the base spur gear element. In anotherembodiment the guide pin element is a separate unit securely mounted tothe shaft of the base spur gear element. In a preferred embodiment, theshaft of the spur gear comprises a hollow and an attachment shaft of theguide pin element is securely pressed therein for attachment to theshaft of the base spur gear element. In a still further embodiment theguide pin element comprises a shaft fixed to the shaft of the spur gearelement and a rotatable cap which rotates independently from the fixedshaft. Generally, the end of the shaft of the pin element is slotted orotherwise configured to accept a tool to enable convenient turning of aguide member which simultaneously turns an opposing guide member foradjusting distance for variable blade thickness.

In a preferred embodiment, the guide member is mounted in a bearing holesized to rotatably secure the shaft of the spur gear element in centeredalignment. The eccentric pin element is generally arranged at the end ofthe shaft to rotate within a circumscribed diameter greater than thediameter of the shaft. Thus, the eccentric pin element generally extendsfrom the remote end of the bearing hole of the spur gear shaft which maybe sized greater than that supporting the spur gear shaft. It should beunderstood however, the invention further contemplates an eccentric pinelement having a diameter sized to enable offset rotation thereof withina circumferential diameter the same or smaller than the diameter of theshaft of the spur gear.

Opposing element sharpening means generally includes a wide variety oftwo or more opposing mounted sharpener elements between which a knifeblade or the like can be drawn for sharpening. The elements may beplates, disks or the like formed to comprise any suitable knife bladeabrading material. Opposing disks may be mounted in a generally staticarrangement, loosely mounted for self adjusting movement or rotatably orthe like driven to assist in abrading. Sharpener elements are generallyarranged so that orientation of the generally “V” shaped drawing slotenables drawing of the blade in a direction generally transverse to theplane of the sharpening elements of the device. Such arrangement ofsharpening elements is well known in the art.

In one embodiment of the invention two or more opposing elements aremounted in generally parallel planes in a partially overlappingarrangement forming a generally “V” shaped slot at the overlappingboundaries. In one arrangement the elements are disks comprising acomposite abrading material along their periphery, the abradingperipheries of the disks forming a curved “V” shaped slot which abradesa curved or hollow ground surface on opposite sides of a blade drawntherethrough. In another arrangement the elements are polygonalcomprising an abrading material along opposing generally straightperipheral surfaces forming a generally angular “V” shaped slot whichabrades a generally straight surface on opposite sides of a blade drawntherethrough.

Particularly in an embodiment wherein a plurality of opposing sharpeningdisks are used, they are generally mounted in two interleaved parallelstacks, forming a generally “V” shaped slot comprises a plurality ofopposing disks, through which a blade of a knife can be slidably drawnfor abrading the sides of the knife blade. Disks can be axle mounted forfree rotation and/or can be enabled for driven rotation by crank,motorized means or the like.

In another embodiment of the invention, opposing polygonal sharpeningblade elements comprising two or more generally straight carbidesharpening edges are mounted in overlapping retaining slots such that asharpening edge of each opposing element defines a leg of a generally“V” shaped slot.

In a preferred embodiment, rectilinear sharpener elements are mountedwithin open ended rectilinear retaining slots arranged in the body ofthe tool so that exposed sharpening surfaces of the elements define legsof the “V” shaped slot, and elements are slidably movable along thelength of the slot. As the sharpening surface of the element wears, theelement can be moved along the length of the slot and its position fixedto provide a fresh sharpening surface to engage the knife blade. Invarious embodiments, a sharpening surface of a rectilinear element isarranged to engage the knife blade along a beveled edge or an edge isarranged to engage a side of a blade at an angle.

In a one preferred embodiment, the quadrilateral rectilinear sharpeningelements have generally parallel, elongate sharpening edges and angledends. Element retaining slots are arranged at about a 40° angle to eachother to define the “V” shaped slot and the elements are slidablemounted in the slots. The ends of the sharpening elements are angled sothat when mounted, the ends lay at about a 90° angle to the centerlinebisecting the “V” shaped slot, enabling convenient variable adjustmentof the positioning of the elements in their respective retaining slotsby various support means engaging the ends, without change to thegeometry or relative position of the “V” shaped slot.

In one particularly preferred embodiment an adjusting screw having agenerally flat end, is arranged along about the plane of the bisectbelow the “V” shaped slot so the flat end simultaneously engages theangled ends of both opposing elements and simultaneously slidably adjustthe position of the elements upward and downward along their respectiveretaining slots to vary the crossing points along the abrading edge ofboth elements forming the apex of the angle of the “V” shaped slot.

In a further particularly preferred embodiment, cam means is arrangedabout perpendicular to the centerline of the bisect, below the apex of“V” shaped slot, to simultaneously support the elements and adjust theposition thereof. In a still further preferred embodiment, a leveredplate, stud, rod or the like engages the ends of the rectilinearsharpening plates to adjust the position of the elements along theirrespective retaining slots.

For a fuller understanding of the device of the present invention,reference should be made to the following detailed description taken inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front sectional view of a sharpening arrangement of theinvention.

FIG. 2 is a top plan view of the sharpening arrangement of FIG. 1.

FIG. 3 is a side sectional view of the arrangement of FIG. 1 taken alongabout line A-A′ of FIG. 2.

FIG. 4 is a bottom plan view of the mounting block of FIG. 1.

FIG. 5 is a top plan view of an angular sharpening element of theinvention.

FIG. 6 is a cross-sectional view of the sharpening element of FIG. 5,taken along about line B-B′ of FIG. 5.

FIG. 7 is a cross-sectional view of a further sharpening element inaccord with the invention.

FIG. 8 is a front partial sectional plan view of a sharpener elementscrew adjustment arrangement of the invention.

FIG. 9 is a front sectional plan view of a sharpener element leveradjustment arrangement of the invention.

FIG. 10 is a perspective view of the lever adjustment means of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1-4, wherein is illustrated an embodiment of thesharpening arrangement of the invention.

Therein a sharpening tool embodiment of the sharpening arrangement ofthe invention is illustrated as comprising a housing 10, with sharpeningarrangement mounting block 15, contained between opposite sides 11 and12 thereof. Mounting block 15 is illustrated as comprising spur gearhollow 13, spaced pinion shaft bearing holes 14 b and 14 c (not shown),blade clearance slot 16, and opposing sharpening element mounting slots17 and 18. Spaced restraining pins 19 and 20 are arranged to extend intomounting slots 17 and 18, to restrict sliding movement of sharpeningelements mounted in the mounting slots.

Opposing quadrilateral sharpening elements 25 and 26, containingrestraining pin slots 25 a and 26 b respectively, are mounted in slots17 and 18, and arranged to overlap so as to form a generally “V” shapedsharpening slot between their respective carbide sharpening edges 25 band 26 b. In the illustrated embodiment, the dimensions from cuttingedge to opposing cutting edge of the sharpening elements closely matewith the width of slots 17 and 18 to resist pivoting of the sharpeningelements in the slot during sharpening and thus resist change in thevertex angle 30 of the “V” shaped sharpening slot formed by thesharpening edges. When the comparative dimensioning of the width of theslots in respect to the mating dimensioning of the width of thesharpening elements is significantly different, the vertex angle of the“V” shaped sharpening slot can change and thus vary the sharpening anglefrom the cutting edge to the side of the blade. The greater thedifference in dimensioning, the greater the vertex change and thegreater the variation in sharpening angle. It is generally considereddesirable for cutting efficiency, that the sharpening angle from thecutting edge to the side of a blade be from about 15 degrees to about 25degrees and most preferably about 20 degrees. Thus, the vertex angle ofthe “V” shaped sharpening slot is preferably from about 35 degrees toabout 45 degrees and most preferably about 40 degrees.

Sides 11 and 12 of housing 10 are illustrated as comprising slots at 11a and 12 a respectively, adjacent the ends of blade clearance slot 16 ingeneral alignment with the generally “V” shaped slot formed by opposingsharpening edges 25 b and 26 b, to avoid undesirable engaging of a bladebeing sharpened with the sides of the housing.

Guide members are illustrated as comprising base spur gear elements 32(not shown) and 33 respectively, with mating eccentric guide pinelements 35 and 36 respectively mounted thereon. Base spur gear elements32 and 33 comprise toothed spur gears 32 a and 33 a respectively andpinion shafts 32 b (not shown) and 33 b respectively. Spur gears 32 aand 33 a are arranged to matingly engage in spur gear hollow 13 ofmounting block 15 with pinion shafts 32 b and 33 b extending into spacedpinion shaft bearing holes 14 b and 14 c respectively. Guide pinelements 35 and 36 are illustrated as eccentrically mounted to the endsof pinion shafts 32 b and 33 b respectively. Slots 35 a and 36 a areprovided at the ends of guide pin elements 35 and 36 respectively formating engagement with a screwdriver or the like to enable convenientrotation thereof so as to micro-adjust spacing between the pin elementstoward and away from the blade being guided, by rotation of a singleguide member.

Referring now to FIGS. 5-6 wherein is illustrated a top plan view andcross-sectional view respectively of elongate rectilinear sharpeningelement 37 comprising opposing generally parallel cutting edges 37 a and37 b, generally parallel opposing ends 37 c and 37 d, and restrainingpin slot 38 which is arranged generally parallel to the cutting edges.In this embodiment an opposing end is angled to an included angle ofabout 70° to a cutting edge of the element so that when two crossingopposing elements are arranged in retaining slots in a mounting block toform a generally “V” shaped arrangement, the ends of the two elementsbelow the vertex of the generally “V” shaped arrangement can be alignedin a common plane. Such angular arrangement of the generally parallelopposing ends enables convenient simultaneous adjustment of the positionof opposing sharpening elements along their respective mounting slots.

The sharpening element itself is illustrated as a four cornered plateformed from a carbide material with cutting edges 37 a and 37 billustrated as beveled from perpendicular to the plane of the plate. Itshould be understood that the element can be formed from any suitablematerial with the edges comprising any suitable abrading material.

FIG. 7 illustrates a sectional view of a rectilinear sharpening elementwherein the cutting edges 39 are generally perpendicular to the surfaceof the plate forming the element.

Referring to FIG. 8, therein is illustrated a sharpening bladeadjustment embodiment of the invention wherein opposing sharpeningelements 41 and 42, comprising ends 41 a and 42 a respectively andrestraining pin slots 41 b and 42 b respectively, are slidably mountedin sharpening element slots 45 and 46 respectively of mounting block 40.Ends 41 a and 42 a of the sharpening elements are angled from thecutting edges as illustrated in FIG. 5, and threaded adjusting screw 43is arranged to twist through mating threaded hole 44 in mounting block40, aligned along about the centerline of the “V” shaped slot formed bythe sharpening elements to simultaneously engage ends 41 a and 42 a. Thesharpening elements are restricted by restraining pins 47 to slidablemovement within sharpening element slots 45 and 46 to the length ofrestraining pin slots 41 b and 42 b respectively. Twisting adjustingscrew 43 into threaded hole 44 engages ends 41 a and 42 a of sharpeningelements 41 and 42 and forces the sharpening elements to simultaneouslyslide upwardly along sharpening element slots 45 and 46, changing thepoint along their respective cutting edges which engage a knife blade tobe sharpened, but maintaining the spacial position and the angle of thevertex of the “V” shaped slot formed by the sharpening elements.

Referring to FIGS. 9-10, wherein is illustrated a further sharpeningblade adjustment embodiment of the invention wherein opposing sharpeningelements 51 and 52, comprising ends 51 a and 52 a respectively andrestraining pin slots 51 b and 52 b respectively, are slidably mountedin sharpening element slots 55 and 56 respectively of mounting block 50.Ends 51 a and 52 a of the sharpening elements are angled from thecutting edges with levered sharpening element adjustment means arrangedto engage ends 51 a and 52 a for simultaneous movement of the sharpeningelements through the length of restraining pin slots 51 b and 52 brespectively.

The levered sharpening element adjustment means is illustrated ascomprising an arm hook, wherein a first end of arm 57 comprises leverextension 57 a and mounting opening 57 b, and an opposite end compriseshook rod 57 c extending angularly therefrom, arranged to engage the endsof the opposing sharpening elements. The arm hook is illustrated asmounted to the sharpening device by screw 58. With screw 58 loosened inplace, lever extension can be depressed to rotate arm 57 so that hookrod 57 c engages the ends of the opposing sharpening elements forcingthem to slide upwardly in slots 55 and 56 to adjust the point ofengagement of the knife blade along the cutting edges of the sharpeningelements and to be locked into place through tightening of the screw.

1. A sharpening tool comprising: opposing sharpening elements arrangedto form a generally “V” shaped sharpening slot; first and secondelongate guide members extending from opposite sides of said sharpeningslot, each comprising a base spur gear element and an elongate eccentricguide pin element; wherein a base spur gear element comprises a mountingshaft having a toothed gear at a first end and an elongate eccentricguide pin element at the opposite end, the toothed gear of said firstguide member arranged in mating engagement with the toothed gear of saidsecond guide member.
 2. The sharpening tool of claim 1 wherein acenterline of a guide pin element is arranged offset from a centerlineof a mounting shaft of a spur gear element of an elongate guide member.3. The sharpening tool of claim 1 wherein said guide pin elements arearranged about equidistant from and generally parallel to a bisectingplane of said generally “V” shaped sharpening slot.
 4. The sharpeningtool of claim 3 arranged so that turning the guide pin element of saidfirst guide member simultaneously turns the guide pin element of saidsecond guide member in aligned mirrored movement.
 5. The sharpening toolof claim 1 wherein said sharpening elements are arranged in off-setoverlapping opposition.
 6. The sharpening tool of claim 5 wherein saidopposing sharpening elements comprise polygonal plates, arranged so thatsharpening edges thereof forms the generally “V” shaped sharpening slot.7. The sharpening tool of claim 6 wherein said opposing sharpeningelements comprise two overlapping quadrilateral plates having abradingedges.
 8. The sharpening tool of claim 5 wherein said opposingsharpening elements comprise disks.
 9. The sharpening tool of claim 8wherein a plurality of opposing sharpening disks are generally mountedin interleaved about parallel stacks, forming the generally “V” shapedsharpening slot.
 10. The sharpening tool of claim 8 wherein said disksare rotationally driven.
 11. The sharpening tool of claim 8 wherein saiddisks comprise a cylindrical abrading surface.
 12. The sharpening toolof claim 5 wherein said disks comprise an abrading edge.
 13. Thesharpening tool of claim 1 wherein said the angle of the vertex of saidgenerally “V” shaped sharpening slot, is from about 35 degrees to about45 degrees.
 14. The sharpening tool of claim 12 wherein said the angleof the vertex of said generally “V” shaped sharpening slot, is about 40degrees.
 15. The sharpening tool of claim 1 wherein said first andsecond guide members support a knife blade along about the bisect planeof said generally “V” shaped sharpening slot.
 16. The sharpening tool ofclaim 1 wherein a guide pin element is configured to engage a tool forturning.
 17. The sharpening tool of claim 1 wherein an eccentric guidepin element is arranged to circumscribe a diameter greater than thediameter of the shaft of the spur gear element.
 18. The sharpening toolof claim 1 wherein the shaft of the spur gear element comprises a hollowand a shaft of the guide pin element is securely pressed therein forattachment thereto.
 19. The sharpening tool of claim 1 wherein a guidepin element comprises a rotatable cylindrical surface.
 20. Thesharpening tool of claim 7 wherein a sharpening element comprises aquadrilateral plate having generally parallel sharpening edges andgenerally parallel angled ends, said ends being angled so that whensharpening edges of the plates are arranged to form the generally “V”shaped sharpening slot, the ends thereof lay at about a 90° angle to acenterline bisecting the “V” shaped sharpening slot.
 21. The sharpeningtool of claim 20 comprising screw means arranged to adjustably engageadjacent angled ends of sharpening elements retained in a generally “V”shaped orientation.
 22. The sharpening tool of claim 20, comprising alevered means arranged to adjustably engage adjacent angled ends ofsharpening elements retained in a generally “V” shaped orientation. 23.A sharpening tool comprising: a mounting block, comprising slotsarranged for mounting opposing sharpening elements comprisingoverlapping rectilinear plates having sharpening edges arranged in agenerally “V” shaped sharpening slot arrangement; first and secondelongate guide members extending from said mounting block on oppositesides of said sharpening slot, each guide member comprising a base spurgear element and an elongate eccentric guide pin element; said base spurgear elements comprising a mounting shaft having a toothed gear at afirst end and an elongate eccentric guide pin element at the oppositeend; wherein the toothed gears of said first guide member is arranged inmating engagement with the toothed gear of said second guide member in ahollow of said mounting block.
 24. The sharpening tool of claim 23wherein said sharpening elements have generally parallel sharpeningedges and generally parallel angled ends, said ends being angled so thatwhen sharpening edges of the plates are arranged to form the generally“V” shaped sharpening slot, the ends thereof lay at about a 90° angle toa centerline bisecting the “V” shaped sharpening slot.
 25. Thesharpening tool of claim 24 comprising screw means arranged toadjustably engage adjacent angled ends of sharpening elements retainedin a generally “V” shaped orientation.
 26. The sharpening tool of claim24, comprising a levered means arranged to adjustably engage adjacentangled ends of sharpening elements retained in a generally “V” shapedorientation.
 27. A quadrilateral plate sharpening element comprisingopposing generally parallel sharpening edges and opposing generallyparallel angled ends, said ends being angled to said edges so that whensharpening edges of opposing plate sharpening elements are arranged toform a generally “V” shaped sharpening slot, ends of the opposing plateslay at about a 90° angle to a centerline bisecting the “V” shapedsharpening slot.
 28. A sharpening element of claim 27 wherein anincluded angle of an angled end to a sharpening edge is about 70degrees.